A fun little game, but definitely needs more work on the tower powers. I was doing quite fine with just the two first levels, the expensive ones were weak on the defense and not very productive either, so felt like a waste of money.
The nudge tower has indeed little use unless you want to just defend and see how many waves you can stand (and probably should have more defense). Poison+flamethrower are OP if you place them far enough from the colony.
